Micro-Electro-Mechanical Systems (MEMS) devices can include various sensors, such as gyroscopes and accelerometers, which can be implemented in various control system and inertial navigation applications, such as in an Inertial Measurement Unit (IMU). A MEMS gyroscope or accelerometer may include microstructure sense elements such as a proof pass interposed between a pair of sense plates, forming a capacitive sensor.
The operation of a MEMS sensor can be disrupted or stopped when subjected to very high levels of shock or vibration. One identified cause for this operational failure is contact between the proof mass and one or both of the sense plates that the proof mass oscillates. When a proof mass to sense plate contact occurs, charge is exchanged and disruption or loss of the sensor signal can result.
Currently, MEMS sensors rely primarily on the proof mass supporting springs, having stiffness in the direction perpendicular to the proof mass plane, to prevent the proof mass from touching the sense plates. Other attempted solutions for preventing proof mass touch to sense plate include electrical damping, and gas damping by filling the evacuated void of the sensor cavity with a rarified gas. However, both of these solutions can be defeated when acceleration forces seen at the sensor exceed certain levels, as presented in certain applications.
In other approaches, the sensor proof mass is held stationary or nearly stationary during high adverse acceleration, and then released for normal operation after the disturbance has passed. The sensor, however, is non-operational during the period of being held stationary.